1. Field of This Invention
This invention relates to the field of encoding art objects, identification cards and the like, and decoding such codes on such articles.
2. Prior Art
U.S. Pat. No. 3,621,250 (Wertzstein) teaches a coding system involving a plurality of coded spots, with the code at each spot including the presence or absence of certain predetermined elements which indicate the sequence in which the information derived from those spots is to be considered. More specifically, each dot contains certain elements which indicate its digital value and other elements which indicate units, tens, hundreds and the like, so that the number 1,234 will be read even if the individual integers are read in the sequence 4, 2, 1, 3. Wertzstein, therefore, teaches the inclusion in a spot of a code which relates to what is read from other spots. Wertzstein speaks in terms of "sequence". In point of fact, what is involved in the disclosure of Wertzstein is simply a coding system for individual spots which, through the use of certain coding elements to indicate units, tens, hundreds, etc., expands the coding breadth. This is brought out by substantially contemporaneous U.S. Pat. No. 3,666,946 (Trimble) which appears to disclose essentially the same thing as Wertzstein but without using the "sequence" language.
U.S. Pat. No. 2,957,079 (Edholm) teaches a method of identifying successive articles by coding and decoding. Code members of a plurality of metal particles are applied in intelligence conveying configuration on the articles. The successive members are subjected to exciting rays to cause the particles to emit secondary rays characteristic of the coded metallic content of the members. The emitted rays are detected to produce an output signal indicative of the intelligence thus decoded from the metallic particle content of the member.
See Leonowich, J., et al., "Radioisotope Sources For X-ray Fluorescence Analysis", J. of Radioanalytical Chemistry, Vol. 40, (1977), pp. 175 to 187.
See also U.S. Pat. Nos. 3,169,186; 3,051,836; 3,444,517; 3,486,006; 3,500,047; 3,663,813; 3,473,027 and 4,146,792.